Navbar glitch on first browser load


I am having a glitch on a website I am currently developing. The side menu (navbar) opens and immediately closes the first time the browser loads it. Subsequent reloads work ok, i.e. the glitch does not happen again. Of course, by default, the side menu is supposed to be hidden. I found somebody else reporting a similar (maybe even the same) problem: Navbar pops in/glitches in Chrome?

Notice: you won’t be able to see the glitch from the Webflow preview. The glitch only happens when the website is deployed - you can take a look at the glitch here:

Unfortunately, even after reading the solution to the similar issue reported above I could not fix the glitch. Is anybody willing to help?

Here is my read-only link: read-only link

Thank you,